Demo Event Registration dialog is returning access denied

Problem/Motivation

Demo Event Registration dialog is returning access denied

The issue the webform page is disabled which triggers a 403 error

@see \Drupal\webform\WebformEntityAccessControlHandler::checkAccess

Proposed resolution

Fix access controls to prevent 403 when webform page is disabled but source entity is provided.

This issue needs to be resolved after #3006867: Refactor the Webform module's usage of AccessResults and simplify cacheable dependency management is committed

Remaining tasks

Fix issue
Write test